Radio range



Apyazz,

s. BOND 2,238,965

RADIO RANGE Filed April 29, 1939 nventor .Donald Bond Patented Apr. 22, '1941 RADIO RANGE Donald S. Bond, Philadelphia, la., assignor to Radio Corporation of America, a corporation of Delaware Application Apr129, 1939, Serial No. 270,829

(Cl. Z50-11) 5 Claims.

This invention relates to radio ranges and more particularly to a radio range in which the overlapping fields include both complementary telegraphic signals and distinctive modulation frequencies.

Radio ranges are transmitting devices by means of Which overlapping radio frequency fields are established. In the overlapping region, signals of equal potential correspond to a desired course for mobile devices, such as aircraft and the like. In general the radio ranges have been either of the aural type in which complementary Morse characters are used, or of the visual type in which distinctive modulation frequencies are employed. It has been found that each type of range has its distinctive advantage. The advantage of the aural type is that the eyes of the pilot are not burdened by observing visually an additional instrument; the advantage of the visual type is primarily a matter of increased accuracy for instrument landing of aircraft.

Thus it is indicated that it would be advantageous to combine both types of signaling in a radio range. In attempting such combination .certain difliculties are experienced and this invention is directed to the solution of these difliculties. It is desirable to avoid key clicks and it is also desirable to synchronize exactly the two types of signals. It is therefore one of the objects of the invention to provide means for modulating simultaneously a radio range transmitter with telegraphic and audio modulation signals. Another object of the invention is to provide means whereby a single radio range may be used to transmit complementary Morse signals and distinctive audio frequency modulation. It is a further object of the invention to provide a radio range in which one of the complementary Morse signals includes a distinctive audio signal while the other Morse signal includes a diiierent audio signal.

The invention will be described by referring to the accompanying drawing in which Figure 1 represents the characteristic eld pattern of the radio range of this invention, and Figure 2 is a schematic circuit diagram representing the invention.

Referring to Fig. 1, if the antenna array A-A radiates the gure-of-S represented by the reference numeral I and the antenna array B-B radiates the figure-of-S field represented by the reference numeral 3, it Will be seen that overlapping elds are obtained. These elds are represented by the shaded portion of the gure. Ii the first mentioned iield l includes a modulation frequency f1 and a telegraphic signal E (dot), it follows that lthe overlapping portion will include the modulation frequency f1 and the dot signal. Likewise, immediately after radiation of the iirst held, the second mentioned field, including the frequency f2 and a T (dash) signal is radiated. The modulation components of the second eld Will likewise be applied to the overlapping portion and a radio receiver located on the line through the center of the overlapping portion will respond equally to both elds including the modulation f1, f2 and the Morse signals E, T which are made complementary so that a long dash is heard. The receiver may include in its output a conventional Sound indicating device and a suitable meter, so that the radio range or course may be followed by aural or visual signals.

A suitable apparatus for practicing the invention is represented by Fig. 2. A radio range transmitter 5 is connected to ground and to the center contact 1 of a link circuit relay 9. The link circuit relay is operated by a pair of field windings Il, I3 and a rotating commutator I5 which may be driven by any suitable type of motor. The link circuit relay includes a pair of xed contacts l1, I9. The latter of these contacts is connected to an antenna array A and the former is connected to an antenna array B. These connections may be made through suitable transmission lines and transformers which have not been shown. A capacitor C1 is connected t0 the transmission line to the antenna array B and through a resistor R1 to a voltage divider R3, R4.

The transmission line to antenna array A is connected through a capacitor C2 and a resistor R2 to the voltage divider. A pair of diode rectiers V1, V2 are connected so that their cathodes are joined to the opposite ends of the voltage diVder R3, R4. v y

The anodes of the diodes are connected, respectively, to resistors R5 and Re which are grounded. These resistors are shunted by capacitors C3, C4. The function of the capacitors is to eliminate or prevent modulation components from being developed across the resistors R5, Re.

The anodes of the diode rectiers are also connected through potentiometers R9, Rio to the control grids of a pair of amplifiers V3, V4. Each of the potentiometers is connected to a transformer T1, T2. The transformers are connected, respectively, to audio oscillators 2|, 23 in which currents of frequency f1 and fz are generated, respectively. The ampliers V3, V4 have their output circuits connected through resistrs to a +B supply. The resistors are Shunted by a pair of capacitors C5, Ca which bypass the radio frequency components which may appear in the outputs of the rectiiiers V1, V2 and hence be applied through the input to the output of the amplier tubes. A pair of capacitors Cv, Cs are serially connected across the output of the audio tubes. These capacitors are of an appropriate valu-e for transferring audio frequency currents. The

junction of the two capacitors is grounded through a potentiometer 25. Slidable contact of the potentiometer is connected to the input circuit of an amplifier V5. The output of the last mentioned 'amplifier is connected through a transformer 2 to the modulator 29 which may be a portion of the radio range transmitter. j

'Ihe operation of the device is as follows: When the link circuit relay 9 is in the position shown, a Morse T is being applied to the antenna array B. It should be understood that the Morse T represents a radio frequency carrier which is modulated by the frequency fz. At the time the antenna array B is energized, the rectifier V1 will rectify a portion of the energy being applied to the antenna and will derive a direct current which is used to bias off the amplifier V3 and thereby prevent currents of the modulation frequency f1 from being impressed on the modulator 2S. At the same instant that the antenna B is being energized, the rectifier V2 is idle and therefore no cut off bias is applied to the amplifier V4 which passes the modulation currents f2 to the iinal amplifier V5 and hence t0 the modulator 29.

In a similar manner the operation of the cir-l cuit transmits a radio frequency carrier to the antenna array A. This carrier will include a Morse E and the modulation frequency f1. During the interval when the antenna array A is energized, the antenna array B is cut E by the link circuit relay and currents from the audio oscillator 23 or frequency f2 are blocked.

Thus the invention has been described as a radio range in which telegraphic signals and distinctive audio signals are transmitted simultaneously. For purposes of explanation, it has been assumed that the Morse signals will be Es and Ts. It should be understood that any complem'entary signals may be used, for example, As and Ns may be substituted for the E, T signals.

In a similar fashion, any distinctive modulation frequencies within the audio or supersonic frequency range may be used.

I claim as my invention:

l. A radio range including, in combination, a

radio frequency -current source, a modulator including connections to said source, means for keying said source with complementary telegraphicsignals, a means for deriving from the thus keyed radio frequency curr-ents controlling currents, a source of two distinctive modulation frequency currents, and means including said controlling currents for applying one of said modulation currents to said modulator during the keying of said source by one of said telegraphic signals and for applying the other of said modulation currents to the modulator during the keying of said source by the other of said telegraphic signals.

2. A radio range including, in combination, a

radio frequency current source, a modulator including connections to said source, means for keying said source alternately with complementary telegraphic signals, a pair of rectiers responsive respectively to the thus keyed radio frequency currents for deriving controlling currents therefrom, a source of two different audio frequency currents, and means including said rectiers for applying one of said audio currents to said modulator during the keying of said source by one of said telegraphic signals and for applying the other of said audio currents to the modulator during the keying of said source by the other of said telegraphic signals.

3. A radio range including a radio frequency current source, a pair of transmission lines, a link circuit relay for applying alternately said radio frequency current to said lines in complementary relation, a pair of rectiiers connected respectively to said lines for deriving controlling currents, a modulator including connections to said source, a source of current of two distinctive frequencies, and means including said rectiers for applying one of said currents of distinctive frequency to said modulator in synchronism with the said application of radio frequency current to one of said lines and for applying the other of said currents of distinctive frequency to said modulator in synchronism with the said application of .radio frequency current to said other 4. A radio range including a radio transmitter, a pair of transmission lines, a link circuit relay for applying alternately radio frequency currents from said transmitter tosaid lines, means connected to said link circuit relay for applying thereto signal currents to form complementary telegraphic signals, a modulator including connections to said transmitter, sources of audio currents of two frequencies,current controlled means for applying alternately said audio currents to said modulator, rectiers coupled to said lines for deriving controlling currents from the alternately applied radio frequency currents, said controlling currents being synchronized with said alternately applied radio frequency currents, and means for applying said controlling currents to said sources of audio currents so that first one, then the other, of said currents of tWo frequencies are applied to the modulator in synchronism with the application of radio frequency currents to said pair of transmissio-n lines.

5. A radio range including a radio frequency power source, a pair of transmission lines, means alternately connecting one then the other of said lines to said source for applying said radio frequency power to first one, then the other, of said lines, a modulator including connections to said power source, a source of current of frequency f1, a source of current of frequency f2, a pair of channels for applying said currents 0f frequency f1, fa alternately to said modulator, and means respons ive to the radio frequency power applied to said lines for synchronizing the application of the modulation currents to said source with the application of the radio frequency power to said ines.

DONALD s. BOND. 

